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Filed March 22, 1951 July 7, 1953 www@ Patented July 7, 1953 RENEWABLE FUSE Gordon F. Laing, Delavan, Wis., assigner to Economy Fuse and Manufacturing Co., Chicago, Ill., a corporation of Illinois Application March 22, 1951, Serial No. 217,001

(Cl. 26d-132) 6 Claims.

The present invention relates to improvements in renewable fuses.

The present invention is particularly applicable to renewable lag fuses, although the invention is not limited thereto. In lag fuses as at present known and used, it has not been practicable to provide a renewable unit which may be removed from the casing when blown, a new fuse being inserted into that casing. Expressed in other language, in renewable fuses as now known and used, it has not been practicable to provide a renewable cartridge with lag characteristics because there is not sufcient room within the casing for a renewable lag fuse element. It is very desirable from an economy standpoint to save the relatively expensive fiber casing, the heavy copper or brass ferrules, or the heavy contact blades and the holding means therefor, which form parts of the usual types of fuse.

An object of the present invention is to provide an improved fuse combining a renewable cartm ridge having fuse elements therein and a casing therefor having operative contact members in the form of ferrules or contact blades.

A further object is to provide an improved renewable lag fuse having sturdy enclosing elements and contact elements, in combination with a lag fuse element of relatively light and inexpensive construction, which lag fuse element may be readily removed and replaced when desired.

A further object is to provide a sturdy casing having contact terminals well adapted to releasably hold a relatively light and inexpensive fuse element and to provide good electrical connection between said fuse element and said terminals.

A further object is to provide an improved renewable fuse element of relatively light and inexpensive construction which may be readily mounted in or disassembled from a casing of sturdy construction.

Further objects will appear as the description proceeds.

Referring to the drawings- Figure 1 is a sectional view illustrating one embodiment of the present invention, said View being taken along the plane indicated by the arrows I-I oi Figure 2;

Figure 2 is a sectional view of the construction illustrated in Figure 1, Figure 2 being taken along the plane indicated by the arrows 2-2 of Figure 1;

Figure 3 is an end View of the construction shown in Figures 1 and 2, said view being taken in the direction of the arrows of Figure 1;

Figure 4 is a sectional view taken along the plane indicated by the arrows of Figure l;

Figure 5 is a fragmentary View in perspective showing one end of a renewable lag fuse cartridge, such as illustrated in Figures 1 and 2; and

ligurel illustrates a detail of construction.

Referring to Figures 1 to `6 inclusive, the numeral l5 indicates a cartridge of tubular form made up of the tube Iii, which may be of paper or other light and inexpensive material, provided with the end caps I'l, il, which receive the ends of the tube I6. Said end caps I l, II will ordinarily, although not necessarily, be made ci metal and may be relatively light and inex pensive.

Located within the cartridge I5 is a fuse assembly indicated as a whole by the numeral IS, said fuse assembly I8 being made up of the slug I9 of fusible metal which provides a heat reservoir and will preferably be a eutectic alloy.

.Physically and electrically connected to the two ends of the slug I9 are the fuse links 20, 2l), which operate also as heaters for the slug I 9. The fuse links 2d, 2c extend through apertures in the caps Il, l'i and are of suflicient length to project well beyond the ends of the cartridge I5. Disposed withinthe tube I t are the diaphragms 2l, 2|, providing a pocket for the slug I9, and between said diaphragms and the caps I1, II are pockets containing inert powder indicated by the nu merals 22, 22. The diaphragms 2|, 2| may be held apart by means of dimples 23, 23 struck out of the links 2B, 20.

The cartridge I5 with its contents is removably mounted within a casing indicated as a whole by the numeral 2li. The casing 24 includes the tube 25, which may be of relatively sturdy fiber. Disposed within each end of the tube 25 is a collar 26, having a bore coinciding with the interior wall of the tube 25. Pins 26', 26 hold the collars 2li, 2t against turning after said collars have been turned home. The outer end of each of the collars 26, 2B is provided with an externally threaded enlarged portion 2l. Disposed in abutting relationship with the outer ends 0f the portions Zl, 2 of the collars 26, 26 are the slotted plates 28, one oi which is shown in perspective in Figure 6.

Each of the plates 28, 28 is provided with a slot 2s communicating with the periphery thereof and extending across said plate a sufficient distance to receive the bent-over end of a corresponding link 20. Each of the plates 28 is provided with a pair of lugs 3l, 3I adapted to iit within corresponding slots in the ends of the portions 21, 2l of the collars 2t, 25, whereby to hold the plates 28, 28 against turning movement, so as to definitely locate said plates circumferentially with respect to the tube 25.

Each of the bent-over ends 30, 30 of the links 20, 2i) is provided with an open-ended slot 32. Each of the plates 28, 28 is provided with a `screw-threaded hole 33 extending therethrough in a direction parallel vwith the axis of the corresponding plate 28.

Located at each end `of the fuse is a terminal 35 including a blade 35' and a circular plate 36 positioned to co-operate with the corresponding plate 23 to clamp the end 30 of the corresponding fuse link 20. Each plate 36 is provided with projections 36', 36 adapted to t within corresponding depressions 36", 36 in the corresponding plates 28, 28, whereby to denitely locate said plates 36, 36 circumierentially with respect to their corresponding `plates 28, 2B. Each plate 36 is provided with a hole 36 extending therethrough of suflicient size to receive the shank oi a corresponding machine screw 34, which is adapted to be threaded into the hole 33 of the corresponding plate 28 and to be located within the slot 32 of the corresponding -bentover end 30 of each corresponding link 20, whereby to hold the plate 36 of the corresponding terminal 35 .in clamping relationship with the correspond-- ing plate 28 to grip the end 30 oi the correspond ing fuse link 2U. The slots in the ends of the collars 26, 26 for receiving the lugs 3l, 3l of the plates 28 will have their center lines in a single diametrically disposed plane of the casing 24 and the projections 36', 36 in the plates 35 will be so related to the depressions 36, 36 in the plates 28, 28 that the terminal blades 35', 35 will be denitely positioned in alignment with each other.

Located at each end of the fuse is a cap t? which may be made cf relatively sturdy material. Each of said caps is provided with the skirt portion 38 internally threaded to engage the es@ ternal threads on the enlarged portion 2l oi the corresponding collar 26. Each of said 4caps tl' has an end `portion 38 provided with a circular hole 39 of sufficient diameter to receive the head oi? the corresponding machine screw 35i and the blade 35o, oi the corresponding terminal In the embodiment of the invention illustrated in Figures 1 to 6 inclusive, the cartridge id einn bodies lag characteristics due to the mass of the fusible slug I9, whereby reasonable overloads may be carriedA for determinable periods of time. The links 2li, 2t will fuse under conditions approximating short circuit conditions.

The cartridge I may be of relatively light `and inexpensive construction and may be readily mounted within the casing 24 according to the following procedure The cartridge l5 will be slipped into the casing 2&1 and a plate 2d will 4be mounted `on the end 30 oi each link 2D, said ends 36 being loca-ted within the slots 2Q of the plates 23; By reason of the lugs 3l, 3| the plates 23 and consequently' the cartridge l5 will beheld against turning movement. The ends 3i), Sil havn ing been bent over into right angular relationship with the axis of the cartridge IE, the machine screws 3d may be inserted and screwed home -to hold each bent-over end 30 securely between the plates 28 and 36, thereby providing electrical communication between the links 2li, 2li and the terminals 35, 35. The caps 3l may then be turned home to provide a rigid assembly.

When the fuse blows either due to the fusing oi 'the links 2D, 2D or to the fusing of. the slug I9, theV cartridge l5 may be readily removed by reversing the procedure above outlined and a new cartridge iii may be readily inserted.

Though certain preferred embodiments of the present invention have been described in detail, many modiiications will occur yto those skilled in the art. It isA intended to cover all such modi fications that fall within the scope of the appended claims.

I claim:

1. A renewable fuse comprising an inner cartridge having deformable terminal links extending from its opposite ends, a tubular casing enclosing said cartridge including an end closure for said casing including a pair of clamping members, the innermost clamping member being nxed in non-rotatable relation with respect to said casing and having an aperture through which one of said terminal links extends and turns down against said innermost member, the outermost member being disposed against said innermost member so as to confine the turneddown portion of the terminal link between them, and means for clamping the outermost member to the innermost member in non-rotating relation 'thereto so as to 4compress and grip the con fined lportion of said terminal link therebetween, said outermost member comprising an electric terminal end plate for the assembled fuse.

2. The invention as deiind in claim l, in which said outermost member has a knife-blade terminal projecting therefrom.

3. The invention as delined in claim 1, in which said clamping means comprises a threaded element screwed into both of said members through the confined portion of said terminal link.

Li. The invention as deiined in claim 1, in which said clamping means comprises aninternally 'threaded end cap screwed upon said casing.

5. A renewable fuse comprising an inner replaceable cartridge having axially extending terminal links at each of its ends, an open-ended tubular casing within which said cartridge is enclosed, a threaded periphery at the open end of said casing, a keyway extending transversely of said periphery, an end plate closing the open end of said casing having projections engaged in said keyway so as to preclude relative turning movement therebetween, an opening in said end plate through which a terminal link of said cartridge extends, said link being turned to lie against the outer face of said plate, a clamping plate overlying said end plate to confine and clamp the extremity of the terminal link therebetween, both plates and the confined extremity ofthe terminal link having aligned openings through whichscrewthreaded means passes to fasten said plates non-rotatably together, a knife-blade terminalprojecting outwardly in normal relation to said clamping plate, an internally-threaded cap engaged upon the threaded periphery of said casing having means to secure said plates thereto, and a circular opening in said cap to accommodate said knife-blade terminal in free turning relation thereto.

The invention as dened in claim 5, in which opposite ends of the fuse are identically constructed with the knife-blade terminals in axial and planar alignment.

GORDON F. LAING.

References Cited in the le of this patent UNITED STATES PATENTS Number 

